Direct reconstruction from 2-D wavelet coefficients
Y = upcoef2(O,X,wname,N,S)
Y = upcoef2(O,X,Lo_R,Hi_R,N,S)
Y = upcoef2(O,X,wname,N)
Y
= upcoef2(O,X,Lo_R,Hi_R,N)
Y = upcoef2(O,X,wname)
Y = upcoef2(O,X,wname,1)
Y = upcoef2(O,X,Lo_R,Hi_R)
Y = upcoef2(O,X,Lo_R,Hi_R,1)
upcoef2 is a two-dimensional
wavelet analysis function.
Y = upcoef2(O,X, computes the
wname,N,S)N-step reconstructed coefficients of matrix X
and takes the central part of size S. wname is a
character vector or string scalar specifying the wavelet. See wfilters for more information.
If O = 'a', approximation coefficients are
reconstructed; otherwise if O = 'h' ('v' or 'd',
respectively), horizontal (vertical or diagonal, respectively) detail
coefficients are reconstructed. N must be a strictly
positive integer.
Instead of giving the wavelet name, you can give the filters.
For Y = upcoef2(O,X,Lo_R,Hi_R,N,S) is the
reconstruction low-pass filter and Hi_R is the
reconstruction high-pass filter.
Y = upcoef2(O,X, or
wname,N)Y
= upcoef2(O,X,Lo_R,Hi_R,N) returns the computed result without
any truncation.
Y = upcoef2(O,X, is equivalent to
wname)Y = upcoef2(O,X,.wname,1)
Y = upcoef2(O,X,Lo_R,Hi_R) is equivalent
to
Y = upcoef2(O,X,Lo_R,Hi_R,1).
% The current extension mode is zero-padding (see dwtmode).
% Load original image.
load woman;
% X contains the loaded image.
% Perform decomposition at level 2
% of X using db4.
[c,s] = wavedec2(X,2,'db4');
% Reconstruct approximation and details
% at level 1, from coefficients.
% This can be done using wrcoef2, or
% equivalently using:
%
% Step 1: Extract coefficients from the
% decomposition structure [c,s].
%
% Step 2: Reconstruct using upcoef2.
siz = s(size(s,1),:);
ca1 = appcoef2(c,s,'db4',1);
a1 = upcoef2('a',ca1,'db4',1,siz);
chd1 = detcoef2('h',c,s,1);
hd1 = upcoef2('h',chd1,'db4',1,siz);
cvd1 = detcoef2('v',c,s,1);
vd1 = upcoef2('v',cvd1,'db4',1,siz);
cdd1 = detcoef2('d',c,s,1);
dd1 = upcoef2('d',cdd1,'db4',1,siz);
See upcoef.